William Senne pleaded guilty to vehicular homicide in the crash that left Ellen Engelhardt brain damaged until her death

WAYLAND, Mass. — The man who rear-ended the cruiser of a popular state police trooper in July 2003, leaving her severely brain injured until her death eight years later, has pleaded guilty to motor vehicle homicide.

But having already spent about two years in prison for driving drunk in connection with the incident, he won't serve any additional time.

William Senne, 29, was on his way to Cape Cod from Wayland at the time of the early morning crash, which initially left Trooper Ellen Engelhardt in a coma and later in a specialized care facility with a traumatic brain injury, unable to walk or talk. She died June 1, 2011.

Senne, who was 18 at the time of the crash, was reportedly traveling nearly 100 mph when his car slammed into the back of Engelhardt's cruiser, which was stopped with lights flashing in the breakdown lane on Route 25 in Wareham. She had stopped to investigate reports of damage to a guardrail from an earlier accident.

Senne pleaded guilty Wednesday in Plymouth Superior Court and was sentenced by Judge Charles J. Hely to 2 1/2 years with one year to serve. Hely deemed the year already served based on a 25-month sentence Senne received for pleading guilty in 2005 to drunken driving in connection with the case.

He was released from prison in 2007. He has since earned a bachelor's degree in economics and established a real estate business in Cambridge. Senne's family owned property on Bassetts Island in Pocasset until 2007, when it was sold to help pay legal bills and other expenses.

Engelhardt was well-known on Cape Cod, where she often directed traffic at the Exit 7 ramp off Route 6. The interchange was named in her honor in 2009.

In his ruling Wednesday, Hely ordered that Senne perform 500 hours of community service at a brain injury treatment facility.

Plymouth County District Attorney Timothy Cruz's office had recommended Senne receive an additional four to five years in state prison minus the time already served on the earlier charge.

"The judge made a decision, and I certainly respect that decision," Cruz said. "We just disagree."

Cruz's recommendation was based on the egregious nature of Senne's actions as well as his driving record, which includes speeding tickets before and after this incident as well as another accident, he said.

Senne initially lost his license after the crash but had it reinstated in September 2007, according to Massachusetts Department of Transportation spokesman Michael Verseckes.

Senne's license was revoked again under the state's immediate threat provision shortly after he was charged with motor vehicle homicide following Engelhardt's death.

The state Registry of Motor Vehicles is required to revoke a person's driver's license for 15 years for the first conviction for motor vehicle homicide, according to Verseckes.

Senne remains "deeply remorseful for the terrible tragedy that took place more than 10 years ago," according to a statement issued on his behalf by a public relations firm.

"Billy hopes that by once again tendering a plea to the court, Trooper Engelhardt's family will find some degree of closure," according to the statement. "He is firmly committed to being a productive member of society and will continue to grow his business, support charitable organizations and be a positive influence on his family and friends."

Engelhardt's daughter, Lora Tedeman, who previously said she did not want Senne to serve any more time, could not be reached for comment.

Engelhardt's father was a Boston police officer, and she had wanted to join the FBI before becoming one of the first female state troopers in 1981, Tedeman told the Times during a 2006 visit to the care facility where her mother was living.

Engelhardt worked the midnight to 8 a.m. shift out of the South Yarmouth state police barracks for much of her career so she could enjoy the sunshine, Tedeman told the Times.

Engelhardt was the first female Massachusetts trooper to die in the line of duty. State police dedicated a mobile unit to her in 2007 that allows troopers to more quickly process impaired drivers.

In a statement released Wednesday, state police Col. Timothy Alben said his agency appreciated the efforts of Cruz and his staff to speak for Engelhardt and hold Senne accountable.

"That said, we respect the judicial process," Alben said. "We hope, most of all, that the Engelhardt family finds solace in their warm memories of Ellen and in the stellar regard with which her memory is held throughout the Massachusetts State Police. Her sacrifice in the line of duty will forever be in our minds, and we will always grieve for her loss."